The present invention relates to an information memory unit including an information memory medium and a cartridge containing the same.
Recently, optical disks, which are advantageous over magnetic disks, have been put to practical use as information memory media. Each optical disk is contained in a cartridge, which facilitates handling of the disk and protects it from mechanical damage and dust.
In general, the cartridge has an opening portion through which information is processed for the optical disk. A read/write head is brought close to the disk through the opening portion. The opening portion is opened and closed by means of a shutter which is slidably attached to the cartridge. Conventionally, the shutter is mounted on the cartridge by fitting a guide piece, formed by raising part of the shutter, into a guide groove on the cartridge.
In attaching the shutter to the cartridge, the shutter is first mounted on the cartridge, and the guide piece is then bent and fitted into the guide groove.
According to such a method of attachment, however, the guide piece must be bent, thus requiring additional troublesome work and lowering the working efficiency. Since the guide piece is bent after the shutter is mounted on the cartridge, moreover, the bending accuracy is subject to variation. In order to facilitate the bending work, furthermore, the shutter is formed of a relatively thin plate member, which has a low mechanical strength and is susceptible to deformation. In some cases, therefore, the shutter cannot be operated smoothly, due to defective engagement between the guide groove and the guide piece.